FP.
Focal plane.
1. A type of single-use flash bulb designed for use with cameras with focal plane shutters.
FP bulbs produced light very rapidly, though not as rapidly as an electronic flash unit. However, they maintained a steady light output for about 1/60 sec and so were capable of illuminating a scene long enough for both curtains of a focal plane shutter to travel. This allowed them to avoid the flash sync problem.
cf. flash bulb, flash synchronization, focal plane, focal plane shutter, M-sync, X-sync.
2. Also high-speed sync. An electronic flash unit which simulates the effect of an old FP flash bulb. The electronic flash technology is named FP by analogy to the old flash bulbs.
Such flash units produce rapid pulses of light in order to circumvent the X-sync speed limitation of a focal plane shutter camera. For more information please consult the FP flash section of my flash document. FP mode flash is indicated on cameras by a high speed flash sync icon.
cf. flash synchronization, focal plane, focal plane shutter, high-speed sync, type A camera.
Entry last updated 2002-04-19. Term 534 of 1487.
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